MATLAB: How to get this graph to plot correctly

functiongraphplot

f(x) = x^8 − 5x^4 + e^x − 7

I've tried f=@(x)x.^8 – 5*x.^4 + exp(x) – 7; and setting x = [-5:0.1:5]; and then just using the plot function, but it doesnt seem right…

Best Answer

This works for me:

f=@(x)x.^8 - 5*x.^4 + exp(x) - 7;
x = [-5:0.1:5];
plot(x, f(x))

It is essentially your code. What ‘doesn’t seem right’ about the plot?

Related Solutions

MATLAB: Is this not working

First, it appears that you are trying to solve it inside the functions, and that won’t work.

Second, this:

F(9) = 0.01*x(6) + 0.04*x(7) - 0.01*X(9);
                                    ↑ ← HERE

MATLAB is case-sensitive, so ‘x’ and ‘X’ are different.

This works:

function [F] = MyFunc(x);
F = zeros(9,1);
 
F(1) = 300 - x(1) - 50000*x(4).^2;
F(2) = x(1) - x(2) - 50000*x(5).^2;
F(3) = x(1) - x(3) - 50000*x(6).^2;
F(4) = x(2) - x(3) - 25000*x(7).^2;
F(5) = x(2) - 100 - 50000*x(8).^2;
F(6) = x(3) - 100 - 50000*x(9).^2;
F(7) = 0.04*x(4) - 0.01*x(5) - 0.01*x(6);
F(8) = 0.01*x(5) - 0.01*x(8) - 0.04*x(7);
F(9) = 0.01*x(6) + 0.04*x(7) - 0.01*x(9);
end
x0 = [200, 150, 100, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5];
x = fsolve(@MyFunc,x0)'

and produces:

x =
          277.777777777778
          188.888888888889
          188.888888888889
        0.0210818510677892
        0.0421637021355784
        0.0421637021355784
      2.57436435034422e-19
        0.0421637021355784
        0.0421637021355784

MATLAB: How to plot multiple 3d on one graph

Following code works fine

interval = [-5:0.1:5];
x = -5:0.1:5;
y = -5:0.1:5; 
[X,Y] = meshgrid(x,y);
z1 = acos((cos(interval)+cos((interval).')));
z2 = acos(-(cos(interval)+cos((interval).')));
figure(1);
plot3(X,Y,z2)
hold on
plot3(X,Y,z1)

Best Answer

Related Solutions

MATLAB: Is this not working

MATLAB: How to plot multiple 3d on one graph

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